This invention relates to a passive vehicle occupant restraint belt system in which the belt is automatically, easily and effectively transferred between an occupant-restraining and an occupant-releasing configuration in response to opening and closing movements of a vehicle door and, in particular, is transferred substantially fully to the releasing configuration when the door is opened only partway toward the fully open position.
In recent years there have been many proposals for passive occupant restraint systems for vehicles. The most common type of restraint systems are those based on restraint belts, and most of the proposed belt systems include a belt transfer mechanism which is driven by an electric motor or a mechanical lever or gear transmission. Many of the proposed systems, particularly those which use a mechanical drive to transfer the belt, require that the vehicle door be fully open to attain full release of the belt.
There are, of course, occasions when the vehicle door can be opened only partway, such as when the vehicle is parked alongside another vehicle or some other obstruction. This fact has apparently led to reliance on electric motor-driven systems, inasmuch as operation of the motor can be controlled in various ways that are unaffected by door position. In contrast, mechanical systems which transmit movement of the door into movement of a belt transfer device have, as heretofore proposed, involved a direct relationship between the amount of transfer of the belt and the amount of door motion; accordingly, a half open door produces a half released belt with such a device. The development of a good mechanical type transfer device has also been hampered by the fact that there is comparatively litte relative movement between adjacent door and door frame parts in the usual side-hinged vehicle door, while almost all passive restraint belt configurations require large movements of a belt transfer device.